Polyhedral oligomeric silsesquioxanes and polyhedral oligomeric silicate nanostructured chemicals are often immiscible in hydrocarbon polymers. For this reason, it is desirable to incorporate organic functionalities onto the nanostructures for the purposes of compatibilization and controlling reactivity with polymers or biological systems. Traditionally the processes affording the incorporation of organic functionalities have been dictated by the choice of organosilane or has been accomplished through use of hydrosilation, cross metathesis, Heck, Grignard, or other organic manipulations. Despite the amenability of such techniques to economical commercial-scale manufacturing and to operation at pre or post assembly of the nanostructure further simplification and lower cost methods are desired.
For these reasons, an inorganic method for treatment of the silsesquioxane and silicate nanostructures present in polyhedral oligomeric silsesquioxanes (POSS) and polyhedral oligomeric silicates (POS) to render them organophillic was developed. The method involves the introduction of an organic compound containing a positively charged functional group such as a quaternary onium that can ion exchange with counter-ions associated the silicate atoms in the POSS/POS. In this way, the inorganic onium group becomes ionically tethered to the silicate atoms of the nanostructured chemical while the organic groups of the onium solvate and in some cases react with the polymer. The result of the interaction between the onium-modified POSS/POS nanostructured chemical and the polymer can then range from an immiscible mixture to that of a fully compatible and nano-dispersed composite depending on the degree of compatibility achieved.
This invention describes methods of preparing new POSS/POS nanostructured chemical compositions that take advantage of a wide variety of “onium” surfactants for use as compatibilizing and functionally reactive groups on the external surface of the nanostructure. Onium groups have been successfully utilized in the compatibilization of layered mineral-type silicates (e.g. mica, bentonite, hectorite, montmorillonite, laponite) with polymers. A wide variety of onium-based surfactant systems have been developed such purposes (Scheme 1)

In general the term onium is intended to refer to [R4M]+ and [R3HM]+ groups where M=N, P, Se, Te and where all R may be either equivalent or inequivalent or combinations thereof and where organic R groups are selected from alkyl, alkenyl, alkyne, aliphatic, aromatic, or the same containing reactive groups that include alcohol, epoxy, ether, ketone, acid, ester, peroxide, amine, amide, imide, azine, nitrile, isocyante, sulfur, phosphorus, and halides. Commercially important examples of onium groups include: N,N-dimethyammonium stearate, N-methylammonium distearate, benzylmethylammonium stearate, tetramethyl ammonium, trimethyl ammonium, tetraethylammonium, triethyl ammonium, benzyltrimethyl ammonium, methyldihydroxyethyltallow, and tetramethylphosphonuim. Onium systems are most commonly utilized as surfactants and thus are commonly referred to as such by those skilled in the art.
Prior art with POSS/POS nanostructured chemicals has shown that they can be incorporated in all three dimensions at the nanoscopic level in polymers. The principal advantage of onium surfactant modified POSS systems is their lower cost relative to POSS/POS systems derived from organosilanes, siloxane, or silsesquioxane sources. Some of the onium groups may also exhibit biocidal activity or related biological activity and thereby be additionally advantageous for commercial markets. Additionally some onium surfactants can subsequently be removed using thermal or chemical methods. Treatment of surfactant modified POSS/POS systems in a similar manner would render uniformly dispersed nanosilica particles ranging in size from 0.7 nm to 10 nm. When incorporated into man-made or biological materials, surfactant modified POSS/POS chemicals can result in increased scratch and mar resistance, improve processability, reduce viscosity, improved fire retardancy, improved permeability, reduced shrinkage and thermal expansion characteristics. The invention is not limited to any specific class of nanostructures, rather it utilizes monodisperse nanosizes, and distributions of nanosized reinforcements, to improve the physical characteristics of glassy, crystalline, amorphous, semicrystalline, rubbery and optical polymers. The resulting nano-alloyed polymers are wholly useful by themselves or in combination with other polymers or in combination with macro- and nano-scopic reinforcements such as fiber, clay, glass mineral and other fillers.
It has long been recognized that the morphology of polymers can be controlled to a high degree through variables such as composition, thermodynamics, and processing conditions. It is similarly known that the usage of fillers (e.g. calcium carbonate, silica, carbon black, etc.) of various sizes and shapes can be utilized to effectively control both polymer morphology and resulting physical properties. Furthermore it has been calculated that as filler sizes decrease below 50 nm they are more resistant to sedimentation and are more effective at providing reinforcement to polymer systems. The full application of this theoretical knowledge however has been thwarted by the lack of a practical source of particulates with monodispersity and diameters below the 10 nm range.